Exploring the oxidation behavior of undiluted and diluted iron particles for energy storage: Mössbauer spectroscopic analysis and kinetic modeling

Iron is an abundant and non-toxic element that holds great potential as energy carrier for large-scale
and long-term energy storage. While from a general viewpoint iron oxidation is well-known, the detailed
kinetics of oxidation for micrometer sized particles are missing, but required to enable large-scale
utilization for energy production. In this work, iron particles are subjected to temperature-programmed
oxidation. By dilution with boron nitride a sintering of the particles is prevented enabling to follow single
particle effects. The mass fractions of iron and its oxides are determined for different oxidation times
using Mo¨ssbauer spectroscopy. On the basis of the extracted phase compositions obtained at different
times and temperatures (600–700 1C), it can be concluded that also for particles the oxidation follows a
parabolic rate law. The parabolic rate constants are determined in this transition region. Knowledge of
the particle size distribution and its consideration in modeling the oxidation kinetics of iron powder has
proven to be crucial.